'\" te
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.\" Copyright 1989 AT&T
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.TH SETLOCALE 3C "Sep 19, 2005"
.SH NAME
setlocale \- modify and query a program's locale
.SH SYNOPSIS
.LP
.nf
#include <locale.h>

\fBchar *\fR\fBsetlocale\fR(\fBint\fR \fIcategory\fR, \fBconst char *\fR\fIlocale\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBsetlocale()\fR function selects the appropriate piece of the program's
locale as specified by the \fIcategory\fR and \fIlocale\fR arguments. The
\fIcategory\fR argument may have the following values: \fBLC_CTYPE\fR,
\fBLC_NUMERIC\fR, \fBLC_TIME\fR, \fBLC_COLLATE\fR, \fBLC_MONETARY\fR,
\fBLC_MESSAGES\fR, and \fBLC_ALL\fR. These names are defined in the
<\fBlocale.h\fR> header.  The \fBLC_ALL\fR variable names all of a program's
locale categories.
.sp
.LP
The \fBLC_CTYPE\fR variable affects the behavior of character handling
functions such as \fBisdigit\fR(3C) and \fBtolower\fR(3C), and multibyte
character functions such as  \fBmbtowc\fR(3C) and \fBwctomb\fR(3C).
.sp
.LP
The \fBLC_NUMERIC\fR variable affects the decimal point character and thousands
separator character for the formatted input/output functions and string
conversion functions.
.sp
.LP
The \fBLC_TIME\fR variable affects the date and time format as delivered by
\fBascftime\fR(3C), \fBcftime\fR(3C), \fBgetdate\fR(3C), \fBstrftime\fR(3C),
and \fBstrptime\fR(3C).
.sp
.LP
The \fBLC_COLLATE\fR variable affects the sort order produced by collating
functions such as \fBstrcoll\fR(3C) and \fBstrxfrm\fR(3C).
.sp
.LP
The \fBLC_MONETARY\fR variable affects the monetary formatted information
returned by \fBlocaleconv\fR(3C).
.sp
.LP
The \fBLC_MESSAGES\fR variable affects the behavior of messaging functions such
as \fBdgettext\fR(3C), \fBgettext\fR(3C), and \fBgettxt\fR(3C).
.sp
.LP
A value of "C" for \fIlocale\fR specifies the traditional \fBUNIX\fR system
behavior. At program startup, the equivalent of
.sp
.LP
\fBsetlocale(LC_ALL, "C")\fR
.sp
.LP
is executed. This has the effect of initializing each category to the locale
described by the environment "C".
.sp
.LP
A value of "" for \fIlocale\fR specifies that the locale should be taken from
environment variables. The order in which the environment variables are checked
for the various categories is given below:
.sp

.sp
.TS
box;
c | c | c | c
l | l | l | l .
Category	1st Env Var	2nd Env Var	3rd Env Var
_
LC_CTYPE:	LC_ALL	LC_CTYPE	LANG
_
LC_COLLATE:	LC_ALL	LC_COLLATE	LANG
_
LC_TIME:	LC_ALL	LC_TIME	LANG
_
LC_NUMERIC:	LC_ALL	LC_NUMERIC	LANG
_
LC_MONETARY:	LC_ALL	LC_MONETARY	LANG
_
LC_MESSAGES:	LC_ALL	LC_MESSAGES	LANG
.TE

.sp
.LP
If a pointer to a string is given for \fIlocale\fR, \fBsetlocale()\fR attempts
to set the locale for the given category to \fIlocale\fR. If \fBsetlocale()\fR
succeeds, \fIlocale\fR is returned. If \fBsetlocale()\fR fails, a null pointer
is returned and the program's locale is not changed.
.sp
.LP
For category \fBLC_ALL\fR, the behavior is slightly different. If a pointer to
a string is given for \fIlocale\fR and \fBLC_ALL\fR is given for
\fIcategory\fR, \fBsetlocale()\fR attempts to set the locale for all the
categories to \fIlocale\fR. The \fIlocale\fR may be a simple locale, consisting
of a single locale, or a composite locale. If the locales for all the
categories are the same after all the attempted locale changes,
\fBsetlocale()\fR will return a pointer to the common simple locale. If there
is a mixture of locales among the categories, \fBsetlocale()\fR will return a
composite locale.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fBsetlocale()\fR returns the string associated
with the specified category for the new locale. Otherwise, \fBsetlocale()\fR
returns a null pointer and the program's locale is not changed.
.sp
.LP
A null pointer for \fIlocale\fR causes \fBsetlocale()\fR to return a pointer to
the string associated with the \fIcategory\fR for the program's current locale.
The program's locale is not changed.
.sp
.LP
The string returned by \fBsetlocale()\fR is such that a subsequent call with
that string and its associated \fIcategory\fR will restore that part of the
program's locale. The string returned must not be modified by the program, but
may be overwritten by a subsequent call to \fBsetlocale()\fR.
.SH ERRORS
.sp
.LP
No errors are defined.
.SH FILES
.sp
.ne 2
.na
\fB\fB/usr/lib/locale/\fIlocale\fR\fR\fR
.ad
.RS 26n
locale database directory for \fIlocale\fR
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
CSI	Enabled
_
Interface Stability	Standard
_
MT-Level	MT-Safe with exceptions
.TE

.SH SEE ALSO
.sp
.LP
\fBlocale\fR(1), \fBctype\fR(3C), \fBgetdate\fR(3C) \fBgettext\fR(3C),
.BR gettxt (3C),
.BR isdigit (3C),
.BR libc (3LIB),
.BR localeconv (3C),
.BR mbtowc (3C),
.BR strcoll (3C),
.BR strftime (3C),
.BR strptime (3C)
\fBstrxfrm\fR(3C) \fBtolower\fR(3C),
.BR wctomb (3C),
.BR attributes (7),
.BR environ (7),
.BR locale (7),
.BR standards (7)
.SH NOTES
.sp
.LP
It is unsafe for any thread to change locale (by calling \fBsetlocale()\fR with
a non-null locale argument) in a multithreaded application while any other
thread in the application is using any locale-sensitive routine. To change
locale in a multithreaded application, \fBsetlocale()\fR should be called prior
to using any locale-sensitive routine. Using \fBsetlocale()\fR to query the
current locale is safe and can be used anywhere in a multithreaded application
except when some other thread is changing locale.
.sp
.LP
It is the user's responsibility to ensure that mixed locale categories are
compatible. For example, setting \fBLC_CTYPE=C\fR and \fBLC_TIME=ja\fR (where
\fBja\fR indicates Japanese) will not work, because Japanese time cannot be
represented in the "C" locale's ASCII codeset.
